The account, tweeting under the
handle @okasanman, appeared to make a joke about the
retirement of baseball player Hiroki Kuroda and the similarity of
his name with that of the Governor of the Bank of Japan.

Okasanman has around 76,000 followers and his tweet was quickly
picked up by others, getting 218 retweets, including from several
prominent members of Japan's day trading community.

Soon afterwards, Okasanman tweeted a picture of the baseball
player, appearing to clarify his earlier tweet. The yen did not
move noticeably against the dollar as a result of the tweet.

Hiroki Kuroda, who played in the USA with the New York Yankees
before returning to Japan to finish his career with the Hiroshima
Carp team, announced his retirement in October at the age of 41.

"The Japan Series will be the end. I've decided to hang it
up," Kuroda said, according to the Kyodo News, as quoted by the
New York Daily News. "I’ve been shown an excellent dream with an
excellent team."